implemented native share intent support for android and ios with chat and folder pickers

lib/main.dart

@@ -22,6 +22,7 @@ import 'app.dart';
 import 'background/widget_background_task.dart';
 import 'firebase_options.dart';
 import 'model/account_data.dart';
+import 'share_intent/share_intent_listener.dart';
 import 'state/app/modules/account/bloc/account_bloc.dart';
 import 'state/app/modules/account/bloc/account_state.dart';
 import 'state/app/modules/breaker/bloc/breaker_bloc.dart';
@@ -68,6 +69,7 @@ Future<void> main() async {
       HydratedBloc.storage = storage;
     }),
     AccountData().waitForPopulation(),
+    ShareIntentListener.instance.initialize(),
   ];
 
   log('starting app initialisation...');
@@ -209,6 +211,10 @@ class _MainState extends State<Main> {
                     previous.status != current.status,
                 listener: (context, accountState) {
                   if (accountState.status != AccountStatus.loggedOut) return;
+                  // A pending share would otherwise survive logout and be
+                  // re-applied after re-login with file paths the OS may
+                  // already have evicted from the cache.
+                  ShareIntentListener.instance.clear();
                   // Routes pushed via AppRoutes (e.g. Settings) live on the
                   // root navigator and survive the home swap below, so they
                   // would still cover the Login screen after logout. Pop